more info and download for the album found https://euchaeta.bandcamp.com/album/poles and https://www.youtube.com/watch?v=yNx_v4ZF-AM
according to https://soundcloud.com/euchaeta/the-north-pole and https://www.youtube.com/watch?v=yNx_v4ZF-AM
i think title should be "北極 feat. 和音" and romanized title should be "The North Pole feat. kazune" (added space after feat. as per standardization rules)